September call-ups are just around the corner, so fantasy owners are just days away from having a whole new set of players available for their rosters. The only problem with this is trying to figure out which players will get enough of an opportunity to make an impact.

One player who doesn't seem to have that problem is White Sox prospect Dayan Viciedo. With Carlos Quentin on the disabled list, Viciedo should get plenty of at-bats in Chicago's outfield. And at this time of year, Viciedo presents fantasy owners with the perfect opportunity to score points.

However, it doesn't always work out that way, as Sporting News contributing writer David Pinto points out in his Inside the Numbers column, available for Fantasy Source subscribers. While Pinto says there haven't been too many lasting impressions made by young players late in the season recently, the ones that do make an impact can go big, like Joey Votto did in 2007.

It's too early to call Viciedo the next Votto, even though their names are conveniently close to one another in the MLB player database, but Viciedo does have some things going for him besides guaranteed playing time.

For one, the 22-year-old was productive in Class AAA this season with a .296 average, 20 homers and .491 slugging percentage. For another, Viciedo hit .308 in 38 games last season for the White Sox.

The White Sox expect big things from Viciedo some day, and some of those days could come this September. And for that, it's worth a shot to stash him on your fantasy roster. Then, stay tuned to Fantasy Source throughout the week as more prospects get the call to the majors.

Top Pickups

Mike Moustakas, 3B, Royals. The lefthanded prospect is primed for a late-season surge. He took a 10-game hitting streak into Sunday's action. Moustakas was hitting .514 (18-for-35) with six RBIs in that stretch. A strong September would prime Moustakas' keeper value.

Josh Collmenter, SP, Diamondbacks. Collmenter owns a 1.42 ERA over his last three starts, and that includes 16 strikeouts in 19 innings. Collmenter has graduated from spot starter to full-time mixed-league pitcher.

Top Sleepers

Brandon Allen, 1B, A's. Allen has taken the job at first base from Conor Jackson and will stay there until the next cold spell. But it has been nothing but hot for Allen lately with a 1.190 OPS over the past two weeks. Oakland has seven games this week against the Indians and the Mariners.

Steve Cishek, RP, Marlins. Cishek picked up a couple of saves last week after Leo Nunez struggled. Manager Jack McKeon will probably stick with Nunez, but if Nunez continues to falter, Cishek could see more opportunities. Plus, with Florida playing eight games this week, Cishek might be needed from a workload standpoint anyway.

Rising Hitters

Peter Bourjos, OF, Angels. An August power surge is making the speedy Bourjos look much less one-dimensional -- and keeping prospect Mike Trout at bay.

Brian Bogusevic, OF, Astros. The rookie has forced his way into Houston's everyday lineup by hitting well over .300 since the All-Star break.

Rising Pitchers

Cole Hamels, SP, Phillies.. Sometimes owners are apprehensive about throwing a pitcher back into the lineup after a stint on the disabled list, but that shouldn't be the case with Hamels, who has a two-start week against the Reds and Marlins on tap.

Alex White, SP, Rockies. The hard-throwing former first-round pick has 17 Ks in 21 innings, and his lone win came on the road. That meshes well with a two-start week at Arizona and San Diego. Expect an increase in "adds" for White this week.

Associate Editors Bill Bender and Brad Pinkerton also contributed to this report.